1. Field of the Invention
The present invention relates to an endoscope including a treatment instrument insertion channel into which a treatment instrument is inserted.
2. Description of the Related Art
In recent years, observation and medical treatment have been performed on an affected part in the digestive tract system, the pancreatic and biliary duct system, and the like, with use of an insertion device, for example, a so-called side-view type endoscope (hereinafter simply referred to as an endoscope). The endoscope includes an observation optical system that is provided on a side surface of a distal end portion of an insertion section to be inserted into a subject.
Examples of the treatment for pancreatic and biliary duct system with use of the endoscope may include, in addition to diagnosis treatment in which the biliary ducts or the pancreatic ducts are imaged by an endoscope, examination by an endoscope for the biliary tract that photographs an image inside the biliary ducts (or the pancreatic ducts) and therapeutic treatment in which gallstones in the common bile ducts are removed with use of a balloon, a gripping treatment instrument, and the like.
In such an examination treatment, in some cases, it is necessary to insert, while a distal end of a guide wire is left inside the subject, a proximal end of the guide wire into a treatment instrument insertion channel that is provided in a contrast tube or an insertion section of the endoscope for the biliary tract, and to insert, along the guide wire, the contrast tube or the endoscope for the biliary tract into a papilla.
When the endoscope for the biliary tract is used, the proximal end portion of the guide wire is inserted from the distal end portion of the insertion section of the endoscope for the biliary tract into a treatment instrument insertion channel provided in the endoscope, and is guided out from the treatment instrument insertion port provided in the operation section.
For example, as disclosed in Japanese Patent Application Laid-Open Publication No. 10-192229, an endoscope forceps plug (hereinafter simply referred to as a forceps plug) is attached to the treatment instrument insertion port. The forceps plug prevents sordes and the like inside the body cavity from flowing back through the treatment instrument insertion channel and spouting out when the treatment instrument is not used.